DIFFERENTIAL REQUIREMENTS OF 2 INSECT-CELL LINES FOR GROWTH IN SERUM-FREE MEDIUM

The development of a serum-free medium that supports the growth of cel ls from a Spodoptera frugiperda and a Lymantria dispar cell Line is re ported. A yeast hydrolysate provided the E-vitamin complex, and a comb ination of a meat hydrolysate and tryptose provided most of the free a mino acids required for cell growth. Supplemental cystine and methioni ne were required to achieve maximum cell growth. The serum or serum re placements used in earlier formulations were replaced with commercial lipid preparations and increased levels of iron salts. Although the ce ll growth cycle had a somewhat extended lag phase and the population d oubling time of the S. frugiperda cells was longer than on serum-conta ining medium, the saturation densities were much higher. Spodoptera ce lls grown in this medium replicated the Autographa californica nuclear polyhedrosis virus well, producing 8.71 x 10(6) TCID50 extracellular virus and 4.4 x 10(8) polyhedra/ml culture. The specific activity of t he polyhedra was somewhat less than that of polyhedra produced in inse cts.